Search NASA⌕ Search

SEARCH · Search NASA

Results for “SUNSET”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 37 records · Page 2
All sourcesNASA NTRSDOE OSTI
NASA NTRS1979

The response of stratospheric constituents to a solar eclipse, sunrise, and sunset

The use of measurements combined with detailed stratospheric modeling of time dependent events, to confirm chemical mechanisms and their laboratory rate constants, is examined. Careful simultaneous solutions of these equations have shown a significant daytime variation of ozone down to altitudes of about 30 km that can affect the interpretation of spectral absorption type experiments. The calculated sunset variations of NO and HO show a log linear concentration decay for limited time periods that can be readily converted into atmospheric temperatures by using known reaction rates up to about 70-km altitude. Proposed measurements of the time dependent behavior of NO and NO2 to be made by U2 aircraft at 20-km altitude are also discussed.

Herman, J. R.↗
NASA NTRS1983

Characteristics of Sunset radar

Located in a narrow canyon 15 km west of Boulder, Colorado, the Sunset pulsed Doppler radar was the first radar designed and constructed specifically as a VHF ST radar. The antenna system is a phased array of coaxial-colinear dopoles with computer-controlled phase shifters for each line of dipoles. It operates at a frequency of 40.475 MHz and a wavelength of 7.41M. Peak transmitter power is 100 kW. Aperture efficiency is 0.58 and resistive loss is 0.30 for its 3600 sq m area. The practical steering rate is 1 record/minute/position to any arbitrary antenna beam position. The first clear-air turbulence echoes and wind velocity measurements were obtained in 1974. Significant accomplishments are listed.

Green, J. L.↗
NASA NTRS1989

Stratospheric N2O5 profiles at sunrise and sunset from further analysis of the ATMOS/Spacelab 3 solar spectra

Data obtained by the Atmospheric Trace Molecule Spectroscopy (ATMOS) experiment during the Spacelab 3 (SL3) mission (April 29 to May 6, 1985) indicated the presence of N2O5 in the stratosphere. This paper presents additional analyses of the ATMOS/SL3 spectra carried out to obtain quantitative information on stratospheric N2O5. Results of this analysis include the detection and measurement of weak N2O5 absorption at sunset in the lower stratosphere, the inversion of a precise (about 10 percent) N2O5 sunrise vertical distribution between 25.5 and 37.5 km altitude, and the identification and measurement of absorption by the N2O5 743/cm band at sunrise. Results confirm model predictions that not all of the N2O5 is photodissociated during the day, except in polar regions during the extended daylight of summer.

Rinsland, C. P.↗
NASA NTRS1990

The sunrise and sunset variation of ClO in the lower stratosphere

The abundances of ClO have been measured, in situ, in the lower stratosphere during sunrise and sunset. Measurements were made with an instrument mounted on the NASA ER-2 aircraft, which was flown at an altitude of 20 km and latitudes between 35 and 47 deg N during a morning and an evening flight. The abundances of ClO were observed over a dynamic range of 20 from a detection threshold of 1 part per trillion volume (pptv). These data confirm the sunrise variation of the photolysis of chlorine nitrate that is predicted by a zero-dimensional photochemical model. They also suggest that the absolute photolysis and termolecular formation of chlorine nitrate occur at rates consistent with nominal ClONO2 and NO2 concentrations.

Brune, W. H.↗
NASA NTRS1994

An examination of global variations of sunset NO2 as measured by SAGE II

Global variations of sunset NO2 are examined for the period October 24, 1984 through May 28, 1991 using Stratospheric Aerosol and Gas Experiment (SAGE) II data. Between 60 deg S and 60 deg N declining trends are observed at all latitudes and at all altitudes above 25 km. For the column NO2 above 25 km, the area-weighted integrated trend between these latitudes is -2.5%/year. The largest rates of decline (5%/year) are at mid to high latitudes in each hemisphere. Different temporal behavior is observed with latitude and in the two hemispheres. The largest percentage changes of NO2 from year to year are observed near 40 km at high latitudes and can be as large as 160%. These results and previously reported simulations suggest that a modulating polar source of NO(y) and variations in atmospheric temperature and advective transport both contribute to the observed NO2 variations.

Callis, L. B.↗
NASA NTRS2018

Synoptic Ozone, Cloud Reflectivity, and Erythemal Irradiance from Sunrise to Sunset for the Whole Earth as Viewed by the DSCOVR Spacecraft from the Earth-Sun Lagrange 1 Orbit

EPIC (Earth Polychromatic Imaging Camera) on board the DSCOVR (Deep Space Climate Observatory) spacecraft is the first earth science instrument located near the earth-sun gravitational plus centrifugal force balance point, Lagrange 1. EPIC measures earth-reflected radiances in 10 wavelength channels ranging from 317.5 to 779.5 nm. Of these channels, four are in the UV range 317.5, 325, 340, and 388 nm, which are used to retrieve O3, 388 nm scene reflectivity (LER: Lambert equivalent reflectivity), SO2, and aerosol properties. These new synoptic quantities are retrieved for the entire sunlit globe from sunrise to sunset multiple times per day as the earth rotates in EPIC's field of view. Retrieved ozone amounts agree with ground-based measurements and satellite data to within 3 %. The ozone amounts and LER are combined to derive the erythemal irradiance for the earth's entire sunlit surface at a nadir resolution of 1818 km2 using a computationally efficient approximation to a radiative transfer calculation of irradiance. The results show very high summertime values of the UV index (UVI) in the Andes and Himalayas (greater than 18), and high values of UVI near the Equator at equinox.

Cloud reflectivity↗
DOE OSTI2021

Sunsetting coal power in China

Reducing CO 2 emissions from coal-fired electricity generation in China is critical to limit global warming. Long-term projections of China's electricity supply tend to assume that coal generation will be a mainstay of China's electricity system through 2050, due to limitations in the scalability of hydropower, nuclear, and natural gas generation and the commercial availability of carbon capture and storage. This paper examines the resource, economic, and institutional implications of reducing and replacing coal generation in China with mostly renewable energy and energy storage by 2040. We find that the scale of solar, wind, and storage resources needed to do so is on the order of 100–150 GW/year of solar and wind capacity and 15 GW/year of energy storage from 2020 to 2025, growing to 250 GW/year and 90 GW/year, respectively, from 2025 to 2040. We then also evaluate the sensitivities if coal plants are retired by 2050.

01 COAL, LIGNITE, AND PEAT↗
NASA NTRS1986

Direct computation of orbital sunrise or sunset event parameters

An analytical method is developed for determining the geometrical parameters which are needed to describe the viewing angles of the Sun relative to an orbiting spacecraft when the Sun rises or sets with respect to the spacecraft. These equations are rigorous and are frequently used for parametric studies relative to mission planning and for determining instrument parameters. The text is wholly self-contained in that no external reference to ephemerides or other astronomical tables is needed. Equations are presented which allow the computation of Greenwich sidereal time and right ascension and declination of the Sun generally to within a few seconds of arc, or a few tenths of a second in time.

Buglia, J. J.↗
NASA NTRS1994

Infrared Astronomy with Arrays: The Next Generation; Sunset Village, Los Angeles, CA, Oct. 1993

Conference papers on infrared array techniques and methods for infrared astronomy are presented. Topics covered include the following: infrared telescopes; infrared spectrometers; spaceborne astronomy; astronomical observatories; infrared cameras; imaging techniques; sky surveys; infrared photography; infrared photometry; infrared spectroscopy; equipment specifications; data processing and analysis; control systems; cryogenic equipment; adaptive optics; image resolution; infrared detector materials; and focal plane arrays.

Mclean, Ian S.↗
NASA NTRS1996

The 1988 Arctic Survey, Diurnal Study (Sunrise and Sunset) and Peak Altitude (22 km) Flights for the In Situ Detection of ClO and BrO from the NASA ER-2 Aircraft

Two critical areas of research were addressed successfully by this research. The first involves NASA ER-2 airborne observations of ClO and BrO radical destruction of ozone within the arctic vortex. The second involves the analysis of diurnal variations in ClO, to test the production and loss rates of ClO that constitutes the test for coupling reactions between the chlorine and nitrogen systems. We discuss results from this research in order.

Anderson, James G.↗
NASA NTRS1978

Identification of the nu-2 vibration-rotation band of ammonia in ground level solar spectra

Comparison of infrared solar spectra in the 750 to 950 kayser region obtained during sunrise and sunset shows that a number of features due to the nu-2 NH3 band are present on the sunset spectra but are indicated by only a trace on the sunrise spectra. The sunset path shows approximately 0.007 atm-cm NH3, and the reason for the discrepancy between sunrise and sunset spectra is not known. The ground-based measurements at Denver were obtained with a 0.06 kayser resolution.

Murcray, D. G.↗
NASA NTRS1991

Spectroscopic measurement of HO2, H2O2, and OH in the stratosphere

Stratospheric concentrations of HO2, H2O2, and OH have been retrieved simultaneously from the far-infrared emission spectra obtained with a balloon-borne Fourier transform spectrometer in June 1983 at 32 deg N latitude. Retrieved concentrations of HO2 and H2O2 are reported, along with vertical distributions of OH which were reported in an earlier paper for the afternoon, sunset, and nighttime periods for altitudes from 26 to 38 km. HO2 distributions are obtained with uncertainties that are about the same as OH for the same vertical range and for the afternoon and sunset periods. H2O2 concentration is obtained at an altitude of 30 km for the period that covers afternoon and sunset hours. The retrieved concentrations of these HO(x) species agree well with other individually measured results and the steady state photochemical predictions. The ratio HO2/OH at around 32 km seems to increase from the afternoon period to the sunset period.

Park, J. H.↗
NASA NTRS2011

Covariant C and O Isotope Trends in Some Terrestrial Carbonates and ALH 84001: Possible Linkage Through Similar Formation Processes

Carbonate minerals found on the surface of Mars and in martian meteorites indicate that liquid water has played a significant role in the planet's history. These findings have raised questions regarding the history of the martian hydrosphere and atmosphere as well as the possibility of life. Sunset Crater, Arizona is a dry environment with relatively high evaporation and brief periods of precipitation. This environment resembles Mars and may make Sunset Crater a good analog to martian carbonates. In this study we sought to identify discrete micro-scale isotopic variation within the carbonate crusts in Sunset Crater to see if they resembled the micro-scale isotope variation found in ALH 84001 carbonates. Sunset Crater carbonate formation may be used as a martian analog and ultimately provide insight into carbonate formation in ALH 84001.

Volk, Kathryn E.↗
NASA NTRS1983

Solar control of winter mesospheric echo occurrence at Poker Flat, Alaska

Winter mesospheric echoes are observed between about 55 and 80 km when auroral absorption is present during daylight hours. Relatively steady auroral absorption during sunrise and sunset periods causes a distinct onset and decay signature in mesospheric echo occurrence. The echo onset and disappearance time are shown versus height by the inclined lines for four different dates. The more vertical lines give the visible sunlight height/time curves for both sunrise (SR) and sunset (SS). The data is combined and replotted to give the morning onset height and the afternoon disappearance height as a function of solar zenith angle. Echoes are not observed at the lowest heights in the morning until the solar zenith angle is less than 90 deg. The afternoon echoes at the lowest heights also start to disappear as soon as the solar zenith angle exceeds 90 deg, implying that the solar component which sustains the mesospheric echo is screened by a layer extending up to about 60 km. The morning echo at 73 km onsets near the time of visible sunrise, but in the afternoon the 73 km echo lasts well past visible sunset.

Ecklund, W. L.↗
NASA NTRS1989

New observations of stratospheric N2O5

The unequivocal detection of N2O5 in the stratosphere was reported by Toon et al. based on measurements of the absorption by the N2O5 bands at 1246 and 1720/cm in solar occulation spectra recorded at sunrise near 47 S latitude by the Atmospheric Trace Molecule Spectroscopy (ATMOS) experiment during the Spacelab 3 (SL3) shuttle mission. Additional measurements and analysis of stratospheric N2O5 derived from the ATMOS/SL3 spectra are reported. The primary results are the detection and measurement of N2O5 absorption at sunset in the lower stratosphere, the inversion of a precise (approximately 10 percent) N2O5 sunrise vertical distribution between 25.5 and 37.5 km altitude, and the identification and measurement of absorption by the N2O5 743/cm band at sunrise. Assuming 4.32 x 10(sup -17) and 4.36 x 10(sup -17)/cm/molecule/sq cm respectively for the integrated intensities of the 1246 and 743/cm bands at stratospheric temperatures, retrieved volume mixing ratios in parts per billion by volume (ppbv) at sunrise (47 S latitude) are 1.32 + or - 0.34 at 37.5 km, 1.53 + or - 0.35 at 35.5 km, 1.63 + or - 0.36 at 33.5 km, 1.60 + or - 0.34 at 31.5 km, 1.43 + or - 0.30 at 29.5 km, 1.15 + or - 0.24 at 27.5 km, and 0.73 + or - 0.15 at 25.5 km. Retrieved VMRs in ppbv at sunset (30 N latitude) are 0.13 + or - 0.05 at 29.5 km, 0.14 + or - 0.05 at 27.5 km, and 0.10 + or - 0.04 at 25.5 km. Quoted error limits (1 sigma) include the error in the assumed band intensities (approximately 20 percent). Within the error limits of the measurements, the inferred mixing ratios at sunrise agree with diurnal photochemical model predictions obtained by two groups using current photochemical data. The measured mixing ratios at sunset are lower than the model predictions with differences of about a factor of 2 at 25 km altitude.

Rinsland, C. P.↗
NASA NTRS1994

Mesospheric ozone measurements by SAGE II

SAGE II observations of ozone at sunrise and sunset (solar zenith angle = 90 deg) at approximately the same tropical latitude and on the same day exhibit larger concentrations at sunrise than at sunset between 55 and 65 km. Because of the rapid conversion between atomic oxygen and ozone, the onion-peeling scheme used in SAGE II retrievals, which is based on an assumption of constant ozone, is invalid. A one-dimensional photochemical model is used to simulate the diurnal variation of ozone particularly within the solar zenith angle of 80 deg - 100 deg. This model indicates that the retrieved SAGE II sunrise and sunset ozone values are both overestimated. The Chapman reactions produce an adequate simulation of the ozone sunrise/sunset ratio only below 60 km, while above 60 km this ratio is highly affected by the odd oxygen loss due to odd hydrogen reactions, particularly OH. The SAGE II ozone measurements are in excellent agreement with model results to which an onion peeling procedure is applied. The SAGE II ozone observations provide information on the mesospheric chemistry not only through the ozone profile averages but also from the sunrise/sunset ratio.

Chu, D. A.↗